English title: Quality of Norway spruce stands in Peräpohjola in Northern Finland.

Abstract

The different kinds of injuries in Norway spruce (Picea abies (L.) Karst.) stands was studied in 52 sample plots in Peräpohjola in the northernmost Finland. The age classes of the stands varied from 100 years to over 220 years. Most of the stands were unevenaged, as is usual in the area.

In the younger age classes (121-160 years) majority of the trees were of normal quality or had smaller injuries in all forest types. In age classes over 160 years the trees of merchantable quality decreased markedly in all forest types. The quality of the trees decreases with the age especially because of butt rot, braking of trees and crooks, forks and heart and top decay caused by the injuries. To ensure future quality it would be important that the stand is healthy from the beginning. When old spruce stands of the area are in large extent diseased by the root rot, it is questionable if they can be regenerated using natural regeneration. The spruce stands of the area are also relatively branchy. This could be prevented by growing the young stands dense. Changing the dominant tree species to Scots pine (Pinus sylvestris L.) in the dry upland forest sites could be a way to improve the quality of the forests in the area.